THERMAL DIFFUSION DYNAMIC BEHAVIOR OF TWO-DIMENSIONALAg-SMALL CLUSTERS ONAg(1 1 1)SURFACE

In this paper, the thermal diffusion behavior of small two-dimensionalAg-islands onAg(1 1 1)surface has been explored using molecular dynamics (MD) simulations. The approach is based on semi-empirical potentials. The key microscopic processes responsible for the diffusion ofAg1−5adislands onAg(1 1 1)surface are identified. The hopping and zigzag concerted motion along with rotation are observed forAgone-atom to three-atom islands while single-atom and multi-atom processes are revealed forAgfour-atom and five-atom islands, during the diffusion onAg(1 1 1)surface. The same increasing/decreasing trend in the diffusion coefficient and effective energy barrier is observed in both the self learning kinetic Monte Carlo (SLKMC) and MD calculations, for the temperature range of 300–700 K. An increase in the value of effective energy barrier is noticed with corresponding increase in the number of atoms inAg-adislands. A reasonable linear fit is observed for the diffusion coefficient for studied temperatures (300, 500 and 700 K). For the observed diffusion mechanisms, our findings are in good agreement withab initiodensity-functional theory (DFT) calculations forAl/Al(1 1 1)while the energy barrier values are in same range as the experimental values forCu/Ag(1 1 1)and the theoretical values usingab initioDFT supplemented with embedded-atom method forAg/Ag(1 1 1).